Because every village has some lake frontage and every village has its own quiet pool, every village will have some water view rooms.
This means that some preferred location rooms will also have water views. Getting a room like that is a matter of luck, it cannot be reserved that way. You can reserve one upgrade or the other (preferred location OR water view), and then request the other.
By the way, not all of Martinique is preferred location. Half of Martinique's builidngs are preferred location (24-25-26), and half are not (21-22-23). Trinidad North has only three buildings, and all three are preferred location.